1. Field of the Invention
The present invention relates to lightweight monolithic concrete structures such as columns with ornamental surfaces having modular end cap elements; and, more particularly to a prefabricated glass fiber reinforced monolithic modular hollow lightweight columns and end caps that can be easily handled and transported.
2. Description of the Prior Art
Processes for the manufacture of concrete structures such as columns are well known in the art. Several of the column casting processes cast heavy solid concrete columns. Hollow round cross-sectional, cylindrical columns have been produced by a few prior art workers. However, these cylindrical columns are devoid of smooth or ornate surface features. Rectangular columns are also produced by prior art processes; but they are not monolithic, since individual faces must be held together by external means.
U.S. Pat. No. 1,936,666 to Hall discloses a form for concrete columns. These form-cast, solid concrete columns have an elliptical or rounded shape, or a rectangular or square shape. The only feature provided involves adding length extension pieces, which tends to change the lengths of the sides of rectangular columns. Similarly, elliptical forms may be elongated to produce a more oval ellipse. Such forms are said to be easily removed from the columns after curing by knocking out blocks or wedges. These forms do not facilitate casting of hollow, lightweight concrete columns.
U.S. Pat. No. 3,956,437 to Ellis discloses a method and apparatus for casting a concrete column. A reusable concrete column casting mold includes a sheet of flat, flexible material which can be rolled and erected into a columnar configuration into which concrete is cast. This flat sheet is rolled to engage different slots that create a cylindrical mold for casting concrete. The mold is suited for casting cylindrical solid concrete columns and does not facilitate casting hollow rectangular shaped columns.
U.S. Pat. No. 4,088,808 to Cornwell et al. discloses shaped articles of hydraulic cement compositions with a glossy reflective surface, and reinforced with fiberglass. Shaped articles of hydraulic cement compositions that are reinforced with fiber glass fabric or with chopped fiber glass have a smooth, reflective surface. The shaped articles are produced by mixing of “super” water reducers to the aqueous cementitious slurries followed by casting or spraying into synthetic polymer molds, or molds coated with synthetic polymers, or compositions that are water repellent and do not stick to hydraulic cements. The cement slurry contains water reducers and mats of or chopped fibers of fiberglass. The mold non-sticky polymer mold coating produces surfaces of the shaped article that are glossy, reproducing fine details of the polymer coated mold. The shaped article is not a column having a specified shape. The cast cement article is not said to be hollow.
U.S. Pat. No. 4,496,511 to Virgili discloses a method of molding stone faced pillars and the like. The method of molding stone-faced pillars comprises attaching stone pieces onto a wooden base, covering the surface of said base, not covered by the stone pieces, with Plaster-of-Paris, spraying numerous coatings of latex rubber on the entire base and stone pieces of the pillar and spraying numerous coatings of liquid base fiberglass on said coatings, peeling off said coatings, and laying them in right angular relationship in a right angular mold and finally pouring wet cement onto the stone-faced portions to reproduce the stone faced pillar model. The stones are held in place on a wooden form using glue and the space between stones is filled with Plaster of Paris. Rubber is applied in multiple coatings to form a support system that allows individual faces to be peeled from the wooden frame. Four such faces are held together with the stones facing outward, and are clamped to form a mold. A central pipe is inserted and cement is poured to form a column. The space between the stones contains plaster of Paris, which is easily damaged. The latex support needs to be removed and this removal also may damage the Plaster of Paris, adversely affecting the appearance of the column produced. The pipe may not be readily removable, and the column is not hollow. The cement poured is not reinforced.
U.S. Pat. No. 4,665,673 to Diana discloses a monolithic surface ornamentation of pre-cast reinforced concrete wall. A reinforced concrete wall, such as a road barrier or barricade, has a monolithic surface ornamentation thereon constituted by pigmented cements and grooves simulating mortar joints. This decorated concrete barrier is a New Jersey type highway barrier. Different colored cements are sprayed in the designated portions to create a decorated barrier. This structure is a barrier wall and is not a column. The wall has a solid construction comprising reinforcement. It is neither lightweight nor hollow.
U.S. Pat. No. 4,887,789 to Harris et al. discloses a form for molding columns. This form is used for molding building components, such as columns, having a desired size, shape, and surface features produced by solidifying building materials such as concrete. The form is sculpted from a plastic material such as polystyrene or urethane. The plastic cylinder is hollowed so that the interior of the resulting form has the size, shape, and surface features of the desired building component. The form can be cut into at least two connecting parts prior to or after molding. This allows the form to be easily and more quickly removed from a hardened column. The connecting parts are held together during concrete casting by tightenable bands. The cement is poured into the form, producing solid heavy concrete columns. This form does not produce hollow lightweight columns.
U.S. Pat. Nos. 5,296,187 and 5,308,572 to Hackman disclose methods for manufacturing columnar structures and reinforced cementitious structural members. The method for manufacturing circular or rectangular cross-section reinforced cementitious columnar structures includes: providing a mold having a cavity which corresponds to a shape and size of the columnar structure; placing at least one nonwoven metal fiber mat around the periphery of the cavity; filling the cavity with a slurry of cementitious material containing aggregate having a particle size greater than the size of the interstitial voids of the fiber mat; allowing the cementitious slurry to penetrate the reinforcement fiber mat; curing the slurry of cementitious material; and separating the mold from the reinforced cementitious columnar structure. When a cement mixture with aggregates is poured into the mold, the fibrous mat is infiltrated with cement without aggregates due to the filtering action of the fiber mat. The column produced is only reinforced on the surface with fibers. The column produced is solid and not a hollow cylinder and therefore is not light. The surface of the column is the infiltrated mat, which does not have a high quality ornamental surface. The '572 patent the reinforcing fibers are dispersed throughout the cement mixture.
U.S. Pat. No. 5,445,864 to Neu discloses a method of manufacturing glass reinforced concrete substantially hollow building products. The building product produced is an acoustic dispersive barrier, not a column. Even though the barrier is said to be hollow, the figure depicted in the patent shows that the hollow portion is equal to or less than the thickness of GRC of each face that is folded. Therefore, the weight reduction is only minimal. Since the concrete rapid hardening solution is applied before folding the mold, no joining action occurs between the sides. The GRC applied over the channel essentially prevents the separation of the sides, and the two sides of the barrier are not integrally attached. The surface of the barrier is not ornate or smooth, due to the presence of long length glass fibers in the cement.
U.S. Pat. No. 5,573,348 to Morgan discloses structural members. The structural members include solid and hollow core beams, poles, columns and enclosure structures formed of a cement-based low viscosity slurry infiltrated fiber composite material. The form for casting the concrete structure is lined with loose short fibers or fiber mat and cement slurry is poured to produce a fiber reinforced composite material to form solids or articles, or as a facing for existing articles. Since all the sides of the structure are cast together, there is a possibility that cement slurry will drip down, particularly from vertical and overhanging surfaces. Addition of water reducers or superplasticizers is relied upon to set the cement as soon as possible, to create this monolithic solid or hollow structure. These structures are therefore unsuited for load bearing applications such as free-standing columns. Incorporation of random fibers first in the mold followed by infiltration of low viscosity slurry results in fibers sticking through the surface, forming a rough, poor-quality cast concrete surface.
U.S. Pat. No. 5,599,599 to Minniran et al. discloses fiber reinforced plastic (“FRP”)-concrete composite structural members. A fiber reinforced polymeric shell forms the mold for pouring in concrete for a column. The shell has protrusions, which enter the main concrete core and anchor the shell to the concrete. The fiber reinforced polymeric shell is never removed and is said to protect concrete from corrosion and damage. The column produced is solid. It is not hollow in construction and is, therefore, heavy. The protrusions into the concrete will weaken the concrete core.
U.S. Pat. No. 5,667,744 to Valle et al. discloses a method for fabricating columns. This method produces solid fiberglass columns, which are polymeric materials with fiberglass reinforcement using a unitary reusable mold. The column thus produced is solid, and is not hollow. This process does not produce hollow glass fiber reinforced concrete columns. The process only produces cylindrical columns, and not rectangular columns, since rotation of the mold is required.
U.S. Pat. No. 5,761,861 to Brackett discloses an apparatus and method for forming a reduced weight masonry column. Modular pieces of stonework are transported to work site and bonded by mortar to a central tube member that forms the cavity. The mortar is only applied to a limited depth. This stonework assembly has the appearance or facade of professionally constructed, custom stonework. The assembly is not a glass filled hollow concrete column. It is merely an assemblage of prefabricated stonework pieces.
U.S. Pat. No. 5,902,528 to Spragg discloses a method of making an article from a lightweight cementitious composition. The cementitious composition comprises Portland cement, perlite, chopped polypropylene fiber and air bubble formers. The composition is cast between an inner mold and outer mold to form decorative lightweight cementitious articles. The inner and outer molds are removed when the cementitious is partially cured. The article is not a column, and constitutes decorative articles molded into one piece. The article does not have decorative fine-finish surfaces. The cementitious article does not have glass fiber reinforcement.
U.S. Pat. Nos. 6,295,782 and 6,878,323 to Fyfe disclose a stay-in-place form. This water-impermeable form is made of a resin impregnated multiple layer fabric and cement mixture is poured into the form. The fibers of the fabric elongate due to the weight of concrete mix poured and shrink back as cured cement shrinks. The resin-coated fabric encloses the concrete structure, preventing concrete corrosion. The concrete column poured is solid and is not hollow. The concrete poured does not have glass fiber cement reinforcement. This is not a lightweight concrete column. The '323 patent discloses anchors and stiffeners that penetrate the concrete core. These penetrations generally weaken the concrete core.
U.S. Pat. No. 6,355,193 to Stott discloses a method for making a faux stone concrete panel. This panel includes one or more thin fiber free concrete layers with macro projections that are created to imitate other natural objects such as s tone, brick and the like. The thin concrete shell may be reinforced with a fibrous polyurethane elastomeric lining and optionally a foam lining. The panel formed is a flat fence barrier and is not a column. It is a solid panel and is not a hollow object. The cement panel does not have alkali resistant glass fibers. The surfaces of the panel does not have reinforcing fibers.
U.S. Pat. No. 6,763,640 to Lane discloses prefab brickwork. These prefabricated, lightweight, columnar or rectangular structures may be converted to fencing or stand-alone columns and resemble solid brick and masonry structures built by skilled masons. Modules comprise heavy-duty durable plastic liners with corner reinforcements comprising heavy-duty square plastic tubing, faced with concrete, mortar and exterior brick and mortar. Modules are erected on concrete footings equipped with raised studs that mate with square plastic tubing and embedded anchor bolts which mate with bottom apertures. Ends of rectangular modules are bolted together and columnar faces. Capitols are of same plastic faced with concrete or mortar and brick veneer. Black plastic tubing simulating wrought iron may be disposed along wall tops. Module inner spaces may be ballast-filled. The column is made from ⅜″ plastic with plastic tubing at corners to which brick facing is attached and mortar is applied between the brick facing. This is not a glass fiber reinforced column. Since the plastic interior is flexible and brick facing with mortar attachment is not flexible any application of load to this prefab brickwork delaminates the brick face attachment from the polymeric inner sheet.
U.S. Pat. No. 6,997,427 to Manthei discloses a form for casting concrete block column. This form for casting concrete columns simulates a stack of stone blocks. The form includes first and second side sections, each including two side panels. The side sections are releasably connected together to form a rectangular frame, which has closed and open positions by use of a hinge and may be locked in the closed position. The frame and a base on which the frame rests supports a column side insert. The column side insert has a central opening in which a column is cast. The column side insert imparts a desired appearance to the exterior sides of the cast column. After a column is cast, the side sections are moved to an open position and the column side insert is separated from the column. The form may include inserts for forming passages in the column and for forming one or more notches in the column for receiving fence rails. The block column is cast using a form that has two sections connected by a hinge and a lock on the opposite side. The concrete column is cast as a block and the figure appears to have a hollow central portion. How this central portion is created is not clear. The concrete is poured into the form, not sprayed to form a hollow column. The hinge is opened only after the block column has cured. Removal of this form will be difficult if the block column external surface has a brick like structure and these features have reentrant surfaces and cannot be easily removed. There is no glass fiber reinforcement in the concrete.
U.S. Patent application publication No. 2003/0218265 to Garcia-Gutierrez et al. discloses a mold and process for casting and manufacturing of concrete structural columns. The mold is for casting and manufacturing of concrete structural columns that includes a main cylindrical body and a plurality of mold components placed inside such main body. The main body is cylindrical and has inside cavity with open ends. The casting elements are four linear half-round section portions with sharp ends, wherein such linear half-round section of each portion is coupled and firmly adhered on the internal wall of the main body, so that the flat side of the four portions remains exposed, in order to give the squareness to the column. The process uses a cylindrical mold with semicircular elements with square faces bonded to the interior of the cylindrical mold to create a square mold with chamfered corners. When cement is poured into the mold to fabricate a concrete column, it produces a solid heavyweight concrete column, not a lightweight hollow concrete column. There is no disclosure that the cement used has glass reinforcement fibers.
U.S. Patent application publication No. 2006/0032184 to Almeter discloses a pre-fabricated outdoor column. The pre-fabricated outdoor column assembly has an outer wall that has the appearance of masonry. The pre-fabricated column assembly includes a tubular member with an insert disposed inside the tubular member. The insert has an opening for receiving a mounting post. It is disposed in a spaced apart relation to the ends of the tubular member such that a first space between the insert and the tubular member and a second space between the insert and the tubular member are formed. The insert further comprises a raceway extending from the first end of the insert to the second end of the insert such that a conduit extending from the first space to the second space is capable of being disposed through the raceway. The outer wall of the tubular member is coated with an elastomeric hard shell coating. The prefabricated column is made from polymeric material such as polystyrene, polyethylene, or polyurethane resins and is adhesively bonded at the corners to create a rectangular hollow column. No disclosure is contained by the '184 patent publication concerning glass fiber filled hollow monolithic cast concrete columns.
Internet publication Aristone Concrete Designs at http://www.aristonedesigns.com/ discloses for sale architectural columns, mantles, balustrade, and others recast in concrete, plaster, and glass fiber reinforced concrete (GFRC). Glass Fiber Reinforced (GFRC) columns are cast horizontally in 2 pieces and can be joined at the factory when a one-piece column is desired. Glass Fiber Reinforced Concrete (GFRC) is a high strength, lightweight concrete product manufactured using sand, cement, alkali resistant fiber and an acrylic polymer curing agent. The final product consists of a GFRC shell approximately ½″ to ¾″ thick. The finished product is as much as 75% lighter than a comparable concrete product. GFRC is the ideal product for limited access areas where heavy structural columns and or other concrete products are not practical. GFRC is available in 15 colors with a smooth or coral finish. The product is excellent for painting or staining. The GFRC columns shown in the web catalog are all cylindrical not rectangular in shape. The GFRC columns do not have surface texture that is ornamental. It also does not use two-fiber length structure to fabricate the columns.
Internet publication Architectural Restoration Castings Co. at http://www.arcgfrc.com/ teaches that Glass fiber reinforced concrete (GFRC) is a proven engineered composite building material consisting of Portland cement, aggregate, water, glass fiber reinforcement and additives. The glass fibers reinforce the concrete, much as steel reinforcing bars do in conventional construction. The glass fiber reinforcement results in a product with much higher flexural strength than normal concrete, allowing its use in thin-wall casting applications. Because of its low shrinkage rate, GFRC is ideal for replication of historic designs, whether in terra cotta, cast stone, or other materials. By making molds directly from the existing pieces, the exact shape and appearance of the originals can be faithfully replicated. For building panel construction, GFRC castings are manufactured by spraying a series of layers of polymer-concrete material with glass fiber reinforcement in a female mold. A steel frame is bonded to the casting, allowing the panels to be installed by bolting or welding the frame to the building's structural steel. The flex-anchors, which connect the skin to the frame, allow movement of the skin relative to the supporting structure. The sprayed GFRC is supported by a steel shell that is welded. No disclosure is contained therein concerning a freestanding lightweight GFRC column.
Notwithstanding the efforts of prior art workers to construct lightweight cast reinforced concrete structures such as columns, there exists a need for lightweight rectangular or square cross-section columns having high surface finish ornamental surfaces with decorative projections or depressions. Such lightweight columns must exhibit high strength so that they can be easily transported and handled. The lightweight concrete columns must be modular so that top fixtures of different designs may be accommodated easily to produce decorative columns having a unique design.